Generally, power supplies for hospital carts, also referred to as medical carts, are uninterruptable power supplies that fall under two general categories: AC (alternating current) output or DC (direct current) output. The AC output uninterruptable power supplies provide a flexible configuration for the end-user because they offer 120 VAC outlets for use, similar to the typical 3-prong NEMA-style wall outlet. An example of an AC output uninterruptable power supply is the HC150 series power system provided by Tripp Lite, which may be paired with either a sealed lead acid (SLA) battery or lithium battery. The Tripp Lite AC output uninterruptable power supply has advantages such as fast recharge times, self-cooling (good heat dissipation), high power output and low operational noise. However, the AC systems are generally large and heavy, require AC-rated cables to power the medical cart components (e.g., AC-rated cables have double-insulation requirements for Mains voltage per industry standards, such as the International Electrotechnical Commission/Underwriters Laboratories (IEC/UL) 60601 technical standards for medical electrical equipment), and do not have wide-ranging input (i.e., they have specific input voltages, generally 120 VAC or 240 VAC).
The DC output uninterruptable power supplies are not flexible, in the sense that only very specific DC voltages and connectors can be used for the different equipment installed on the cart. However, DC output uninterruptable power supplies do provide increased efficiencies when running off the battery, which manifests in longer runtimes for the end user. An example of a DC output uninterruptable power supply is the medical-grade Series 301 Motive DC Controller provided by Hoffman Engineered Systems (HES), which are comparably smaller and lighter than their AC counterparts. The HES DC output uninterruptable power supply has advantages such as wide-range inputs, configurable outputs (e.g., DC/DC conversion to a different voltage with a converter or a DC/AC conversion with an inverter), and less wasted power due to conversions to different electrical outputs. However, the power cabling (e.g., power bus) in the cart must be rated for DC voltage per the above-mentioned industry standards, and the DC systems do not provide conversions to AC without an external DC/AC inverter.
While each has its advantages and disadvantages, the medical carts are designed and built around the power system. Thus, the medical cart is either a DC-based system or an AC-based system, thereby inheriting not only the advantages but also the disadvantages. The hardware for the medical cart is specific to either DC components or AC components. Although DC systems are somewhat configurable in being able to accommodate DC/DC converters, both AC and DC systems are limited in terms of configuring the power system and components of the medical cart. That is, the carts were, in part, designed around the power system, rather than the power system being designed around the cart, due to the “off-the-shelf” nature of uninterruptable power supplies from the power supply industry. This leads to less customization of medical carts for the end-user's purposes. The power system, and as a result the medical cart hardware components, are static, and not capable of being easily interchanged without modifying almost every aspect of the medical cart. While AC and DC systems each have their advantages, their respective disadvantages require the manufacturer (or the customer) to make tradeoffs when designing and building the medical cart.
Furthermore, based on the physical configuration of medical carts, the uninterruptable power supply, including the battery, is located in the base of the cart, near the floor, to help lower the cart's center of gravity. Any conversion modules (such as DC/AC inverters) are likewise provided in the base with the power supply, often as units external to the power supply. The end user's equipment (computer, monitor, printer, etc.) is located at the top of the cart with the work platform, close to the end user's upper body. Because of the engineering differences between the AC and DC power cables and connectors (they are not interchangeable), existing medical carts are set up with different stock keeping units (SKUs) for each power system configuration. Some medical carts are available with both AC and DC output power systems, but these configurations are inherently more expensive, and also require both sets of electrical cables and connectors to be routed from the base up to the work platform of the cart. As such, existing uninterruptable power supplies for medical carts prevent cart manufacturers from optimizing the medical carts for productivity, serviceability, and flexibility tailored for the customer.
Thus, there is a need to provide a hospital cart power system that is more flexible in terms of its configuration.